A woman says she wants to challenge a judge's ruling that she used "undue influence" on her mentally ill son but cannot afford to hire lawyers.

Mrs Justice Hogg last week declared a decision made by the man to refuse psychiatric drugs and electro-convulsive therapy invalid, following a hearing in the Court of Protection - where issues relating to sick and vulnerable people are analysed - in London.

She was told that the man - a paranoid schizophrenic - had signed an advance decision refusing any ''psychiatric physically invasive treatment'' including psychiatric drugs, electro-convulsive therapy and ''psycho-surgery'' nearly two years ago.

But Mrs Justice Hogg decided that the man's ''forceful'' mother had exerted undue influence on him.

She decided that the man did not have the mental capacity to make such a ''complex decision'' after social services staff and doctors raised concerns, and a local authority asked for a ruling.

But the man's mother thinks that she has been unfairly treated.

"I didn't use undue influence," said the woman. "I was just trying to make him understand. Mrs Justice Hogg just believed what she was told. But the man she described is not my son."

She added: "I would like to appeal. But how can I? We don't qualify for legal aid because my partner earns too much. But we don't earn enough to pay for lawyers."

Mrs Justice Hogg was told that the woman was unable to get legal aid and had initially represented herself during Court of Protection litigation before lawyers agreed to represent her for free.

The man's interests had been legally represented by court-appointed lawyers.

Mrs Justice Hogg described the man's mother as a ''powerful'' and ''emotional'' woman who believed that anti-psychotic drugs were ''harmful and toxic''.

Her views were well-known to the man and her ''ability to overbear him'' was considerable, said the judge.

The judge was told the man had been severely injured more than 15 years ago. She said he was a tetraplegic and wheelchair-bound. She said he also had mental health difficulties and specialists had diagnosed paranoid schizophrenia more than a decade ago.

Mrs Justice Hogg heard evidence from medical specialists and social services staff involved with the man, and from the man's mother and another family member.

Lawyers representing health and social services officials argued that the man did not have the mental capacity and that his advance decision had been made under the undue influence of his mother.

The man's mother disagreed and argued that the decision should not be declared invalid.

Mrs Justice Hogg analysed evidence at a hearing which began last week and made her ruling on Friday.

The judge ruled that little personal detail about the man could be revealed. She said the man lived in south-east England but his name, age and address could not be made public.

She ruled that the identities of the council and NHS trust could not be revealed in case such information created a jigsaw which led to the man's identity emerging.